"Community spirit is strong and the will of the people will not be broken."

Police said 12 people had been arrested as of midday.

Coffs Local Area Commander, Superintendent Mark Holahan, said police were concerned that some members of the group were risking their safety and that of gas company employees.

"Everyone has the right to protest peacefully. However, when this obstructs traffic, interferes with people's safety and hinders their work, action must be taken," he said in a statement.

"Criminal offences, anti-social behaviour or property damage will not be tolerated.

Greens MP Jeremy Buckingham criticised police for being forceful.

"It's a sad reflection on the coal seam gas industry that police have to arrest local residents and force their way through a community blockade so that they can drill for gas," he said in a statement.

"There is no future for coal seam gas in NSW if each drill rig needs to have a police guard to force its way into communities."

Mr Buckingham said an official poll conducted during the September 2012 local government election confirmed that the overwhelming majority of residents in the Northern Rivers don't want their region turned into a coal seam gas field.

"The Greens congratulate those people who have bravely taken a stand to protect their local community and environment," he said.

"They are not only local heroes, but have the support of the broader community in NSW."